Airfoil construction



June 20, 1950 H. M. wooDHAMs Erm. 2,512,453

AIRFOIL CONSTRUCTION Filed July 19, 1947 5 Sheets-Sheet 1 INVENTORS AHgs. I

I UuIdl JMD l I I I I I I I I I I I I LII I I II II Il |I I :l ,l |I ll 'l II "Il H.M.wooDl-|Ams I Byw. D. Locuwooo June 20, 1950 H. M. wooDHAMs Erm. '2,512,453 I AIRFOIL CONSTRUCTION 3 Sheets-Sheet 2 Filed July 19, 1947 n FIGS INVENTORS. H.M.woooHAMs 4 BY S.w. D. Lockwoob June 20, 1950 H. M. wooDHAMs Erm. 2,512,453

AIRFOIL CONSTRUCTION 3 Sheets-Sheet 3 Filed July 19, 1947 JNVENTRS. H. M. woouHAMs LocKWOOD BYSJM D.

Patented `lune 20, 1950 Herbert M. Woodhams and Sidney D. Lockwood, Coventry, England, assignors to Sir W. G. Armstrong Whitworth Aircraft Limited, Coventry, Warwickshire, England Application July 19, 1947, Serial No.v 762,104 f In Great Britain August 1, 1946l '1 2 onims. (c1. zii-124) Considerable difculty has been experienced in manufacturing the built-up structure of a smooth-surfaced aerofoil, particularly of an aircraft wing, owing to the extremely fine limits of accuracy which are required to avoid disturbing the laminar-air-flow characteristic.

It is also a matter of some difficulty to construct an aircraft wing to enable access to the wing interior (for maintenance purposes) to be easily attained owing to the disturbance to the air-ow caused by inaccuracies in the exterior skin due to .access doors in the upper and/or lower surface.

' The main objects of the invention are to provide an improved aircraft wing and a method whereby the same can be constructed accurately and far more. simply and quickly than has hitherto been possible, the method particularly lending itself to repetition production methods. -IAccording to the invention, an aerofoil has the main portion, at least, of its air-swept surface formedof accurately formed panels, of appropriate curvature, having inwardly-projecting marginal iiangesv rigidly .connectedl together. *l Of L,the accompanying drawings:

Figure 1 .is la.- chord-wise section through one form of aeroplane wing according to the invention, the trailing-edgeportion being omitted and the section being on the line I-l of Figure 2;

Figure 2 is a fragmentary plan, partly broken away, corresponding with Figure 1;

Figures 3, 4 and 5, are, respectively, sections, to a larger scale, on the lines 3 3, 4 4, and l5,--5of-1iigure-1;

' Figure 6 is a detail view, to the same larger scale, illustrating a modified form of the marginal iianges;

Figure 7 is a View corresponding to Figure 3 but showing a method, according to the invention, of securing va chord-wise stiiener in position between two adjacent panels lwithout the stiffener breaking through to the air-swept surface;

' Figure 8 isa sectional detail view showing how a panel, according to the invention, may be recessed along an edge to receive an attachment platee-for example, of a leading-edge portion of awing, a trailing-'edge portion, or a wing tip portion;

Figure 9 is a chord-wise section through another form of aeroplane wing, according to the invention, with the leading and trailing edge portions indicated only by chain lines, the section being taken on the line 9-9 of Figure 10;

Figure l0 is a fragmentary plan of the main portion of the wing of Figure 9, i. e., excluding the leading-edge and trailing-edge portion, and

vening' spar'l.

Figure 11 isasection taken on the line II-II of Figure 10; and

Figure 12 is a fragmentary section showing a methodof attaching an internal stiffener to a rib of the panel.

Throughout the various figures of the drawings corresponding reference characters are used to denote` similar parts aslfar as possible.

Referring to .Figures 1 to 5, the main portion of the wing isy built upfrom a span-wise series of upper and` lower .panelsZl and 22 which are preferablylongerin-the span-wise than in the chord-wise direction of the ,-wing. This series of panels is connected` to a leading-edge portion 23 and to a trailing portion (not shown). Each of` thepanelsfhasv a chord-wise marginal flange 24 at each end and a-span-wise marginal fiange 25 at each.side,.the panels, interiorly of the wing, being somewhatA tray-like in appearance. The

span-wise flanges 25 are, in this instance, shown as being deeper than the chord-wise anges 24. The anges-24 are stayed by triangular gussets 26 (see Figure 3) vand the flanges 24 and 25 have bosses 21 which are drilledto receive fixing bolts, rivets, ror the like. Thedrawings show the use of bolts 28 and nuts 29. y

In constructing the wing, the leading-edge portion 23; (whichvmay be formed of aligned span-wise `sections zbolted togetherthrough flanges 24a thereof as indicatedin Figure 2) is bolted by some of 1the bolts 28 -to the adjacent flanges 25'of the panels 2l and 22 with an intervening spar 30 (which'may be formed of fullspan length, or in sections which may, or may not; terminate at the chord-wise junctions of the panels 2l and' 22).

In a similar-way the trailing-edge portion is secured' to the panels 2| and 22 with an inter- After the main portion of the wing has been assemb1ed,`the`whole of theiouter surface thereof canbe machined, as necessary, tothe desired profile, for instance, on a plane-miller fitted with a lKeller copying device, or some other suitable means. Thepanels, when'of light alloy, may be cast, but are preferably formed'a's bars or strips by extrusion methods, to be greater in thickness than the external height of the iianges 24 and 25. The panels are then machined, in any suitable rnanner at their inner surfaces so as to form the flanges, gussets and bosses and the like. If, on the other hand, the panels are to be moulded, the iianges, gussets, and bosses can be formed during that process.

and stiieners may be provided with'lighteningl holes 33 which also serve to facilitate assembling and dismantling of the wing.

If desired the inner edges of the flanges-24 andV 25 may sweep into the inner surfaces of the panels,V

(so that the roots of the flanges are thicker than their free edges, as shown in Figure 62) and thu-s produce a more rigid flange. With this'conf and 22a. Obviously this stiii'ener, if preferred. need not break through to the wind-swept surface but may be secured in the manner disclosed by Figure '7.

If desired a span-wise stiffener may be associated with one or more of the ribs 40, or with the chord-wise rib 34 (Figure 2), and Figure 12 shows one such arrangement in which the stiffener 43 is V"iianged along its upper edge in order to be secured agairistthe4 inner face of the rib 40 by means oi screws 44.

It will be seen that by the invention a very rigid wing can Abe constructed, the internal iianges and gussets, together with the ridges, when prostruction, however, instead of providing therbosses 21 suitable recesses are formed in the anges to provide parallel surfaces for coaction-withthe heads of the bolts 28 and thecaptive nuts 29.A

In some instances, particularlywhen the panels are relatively long in the span-Wise directiomthey may be provided' with intermediate chord-wise ridges 34 (see Figure 2) and these ridges may be stayed laterally by. gussets 26.

Figure 8 shows a. modi'cationpin which the external surface of a panel` (one ofk the upper panels 2| is chosen' for purposesof illustration) is provided with a machined recess `36' along its edge toy receive a shaped' plate 31 of' some part to be attached to the panel. 'llheplate 31 in'Figure 8 is assumed to' be part off the leading-edge portion; but obviously the samemethod of attachment' may be' appiiedin respect of the trailing-edge portion, or of the wing'tip section'. In this construction the front spar is shown as iitting beneath the plate 31", whichl is securedr in position by means of4 fiush-iittingbolts', as indicated by the chain line 38` Obviously the lower panel 22 will be provided `with av similar recess to receive a corresponding attachment plate.

Access doors may be provided `in the air-swept surface of a panel 2i or'22 inforder to facilitate assembly or for other purposes, these doers pref erably consisting of flush-ttingfplates let into recesses round 'openingsiri the paneland secured by counter-sunk screws or the like; in the manner described above in connection with one edge vof the panel in Figure 8.

Referring now to Figures. 9,.-10. and l1, these show a modification. in which the main portion of the wing, excluding/the' leading andi trailing edge portions, isformed of threeseries'oi upper span-wise panels-21a and.' three seriesofv lower span-wise panels 22a, each lindividual panel being or any convenientspan-wise'length'and all having marginal iianges as previously'described, those extending chord-wise being marked 24-C andV those extending span-wise being marked 2-5; Inl addition, in this constructiomspan-wise ribs` 40 are provided intermediate the spanew-ise-fianges 25. If desired a span-wise stiiienermayfbe mounted between either adjacent series of thepanels. One such stiiTener 4| is shown in Figure 9 as being secured between the intermediate series of panels 21a and 22a and thetrailing series: of panels 2Ia.

vided, the spars and stiffeners providing ample resistance to bending and twisting loads.

v What 4we claim as our invention and desire to secure VbyzLetters Patent of the United States is:

1. An aerofoil of which at least the main part of ,theair-swept .surface comprises at least one span-wise series, of aligned, accuratel-y-,iarmed-l four-sided panels, of, appropriate curvature, having inwardly-projecting marginal'` flanges of. which those at. valternatev sides. are, chord-wiseY of the aerofoil and those atthe-intermediate, sides are span-wise, .at least, one interior chord-wise -ridge toeach panel4 intermediateA its. chord-wise flanges, integral gussets connecting. the. interior. face 0f each. panel to the adjacent surfaces of itschordwise nanges'., integral gussets connectingthe interior face. of each panel toA the-adjacent sides. of its chord-wise ridge, and means connecting adjacentpaneistogether by theirrespective chordwise flanges.

2. Anaeroioil-oi which. atleast the main part of the air-swept surface comprises atleast one span-wise series 'ofA aligned, accurately formed, icursidedpanelsgoi appropriatecurvature, having inwardly projecting marginal,flanges,` means connecting adjacent panels together by their respectivechord-Wise flanges, a spar at one side of said` series,4 said inwardly projecting marginal iiangesl being, removed from' the4 endoi said panel by a distance one-half the thickness of said spar te accommodate said sparso. that the same does not break throughA to therair-swept surface, and means connecting the adjacent span-wise anges of said panels to saidv spar.

` HERBERTM; WOODHAMS.

SIDNEY W; D. LOCKWOOD.

REFERENCES CITED The: following referencesL arev oi." record in the 

